White mold
Sclerotinia sclerotiorum
2 host plants
Last updated
This profile contains verified disease data from extension databases. Regional field notes and expert review are in progress.
Magnolia develops white mold when grown in poorly drained soils or with overhead irrigation. Plant in well-drained soil, avoid overhead watering, and space plants for air circulation. Remove and destroy infected plants. Do not compost diseased material. These preventive practices are your best defense.
Remove affected material as you find it and clean up any fallen debris where white mold spores can overwinter. Improve air circulation around susceptible plants through selective pruning. Avoid overhead irrigation during vulnerable growth periods. If the problem is persistent, your local Extension office can recommend current fungicide or bactericide options for your specific situation.
Quick Reference
Management
Spring through early summer during cool, wet weather. Particular risk on fruit touching soil or infected plant debris. Dead flowers and leaves on living plants serve as entry points.
Cool, wet conditions (59-70°F optimum); extended leaf and soil moisture, high humidity >85% required. Apothecia develop in spring and early summer during cool, moist soil conditions. Soil contact increases infection risk. Disease development not severe in cooler PNW maritime climates. # Source: PNW Plant Disease Management Handbook
Cultural Controls
- Plant in well-drained soils.
- Avoid overhead irrigation.
- Space plantings to improve air circulation, particularly around the base of the plants.
- Remove and destroy infected plants.
- Do not compost diseased plant materials.